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TO POSITION FIRST CAN CAUSE DATA TO BE CORRUPTED". ALTER TABLE MODIFY/CHANGE ... FIRST did nothing except renaming columns if new version of the table had exactly the same structure as the old one (i.e. as result of such statement, names of columns changed their order as specified but data in columns didn't). The same thing happened for ALTER TABLE DROP COLUMN/ADD COLUMN statements which were supposed to produce new version of table with exactly the same structure as the old version of table. I.e. in the latter case the result was the same as if old column was renamed instead of being dropped and new column with default as value being created. Both these problems were caused by the fact that ALTER TABLE implementation incorrectly interpreted both these situations as simple renaming of columns and assumed that in-place ALTER TABLE algorithm could have been used for them. This patch fixes this problem by ensuring that in cases when some column is moved to the first position or some column is dropped the default ALTER TABLE algorithm involving table copying is always used. This is achieved by detecting such situations in mysql_prepare_alter_table() and setting Alter_info::change_level to ALTER_TABLE_DATA_CHANGED for them. mysql-test/r/alter_table.result: Added test for bug #12652385 - "61493: REORDERING COLUMNS TO POSITION FIRST CAN CAUSE DATA TO BE CORRUPTED". mysql-test/t/alter_table.test: Added test for bug #12652385 - "61493: REORDERING COLUMNS TO POSITION FIRST CAN CAUSE DATA TO BE CORRUPTED". sql/sql_table.cc: Changed mysql_prepare_alter_table() to detect situations in which we some column moved to the first position or some column is dropped and ensure that such ALTER TABLE statements won't be carried out using in-place algorithm. The latter could have happened before this patch if new version of table had the same structure as the old one (except the column names).
This directory contains a test suite for the MySQL daemon. To run the currently existing test cases, simply execute ./mysql-test-run in this directory. It will fire up the newly built mysqld and test it. Note that you do not have to have to do "make install", and you could actually have a co-existing MySQL installation. The tests will not conflict with it. All tests must pass. If one or more of them fail on your system, please read the following manual section for instructions on how to report the problem: http://dev.mysql.com/doc/mysql/en/mysql-test-suite.html If you want to use an already running MySQL server for specific tests, use the --extern option to mysql-test-run. Please note that in this mode, the test suite expects you to provide the names of the tests to run. For example, here is the command to run the "alias" and "analyze" tests with an external server: mysql-test-run --extern alias analyze To match your setup, you might also need to provide --socket, --user, and other relevant options. With no test cases named on the command line, mysql-test-run falls back to the normal "non-extern" behavior. The reason for this is that some tests cannot run with an external server. You can create your own test cases. To create a test case, create a new file in the t subdirectory using a text editor. The file should have a .test extension. For example: xemacs t/test_case_name.test In the file, put a set of SQL statements that create some tables, load test data, and run some queries to manipulate it. We would appreciate it if you name your test tables t1, t2, t3 ... (to not conflict too much with existing tables). Your test should begin by dropping the tables you are going to create and end by dropping them again. This ensures that you can run the test over and over again. If you are using mysqltest commands (like result file names) in your test case, you should create the result file as follows: mysql-test-run --record test_case_name or mysqltest --record < t/test_case_name.test If you only have a simple test cases consisting of SQL statements and comments, you can create the test case in one of the following ways: mysql-test-run --record test_case_name mysql test < t/test_case_name.test > r/test_case_name.result mysqltest --record --record-file=r/test_case_name.result < t/test_case_name.test When this is done, take a look at r/test_case_name.result - If the result is incorrect, you have found a bug. In this case, you should edit the test result to the correct results so that we can verify that the bug is corrected in future releases. To submit your test case, put your .test file and .result file(s) into a tar.gz archive, add a README that explains the problem, ftp the archive to ftp://support.mysql.com/pub/mysql/secret/ and send a mail to bugs@lists.mysql.com